For veterinarians in diagnosing injuries to large animals, in the field, especially race horses, it is important that the X-ray plate be held in a reasonably immobilized position for approximately one-twenty-fifth to one-tenth second while the X-ray camera is being used.
While this can readily be done with large animals that are hospitalized or anesthesized, for early diagnosis in the field the animal may merely be held in a standing, upright position. Over 90 percent of the X-rays taken of large animals under these conditions are X-rays of injuries to the knee or ankle of the animal.
Usually the animal, especially in the case of race horses, is tempermental, does not wish to maintain a quiet, fixed position for a very long period of time and can injure anyone who is holding the X-ray film.
It is the current practice in the field for a technician or veterinarian's assistant to hold the film behind the portion of the animal to be X-rayed in order to maintain the X-ray film in a reasonably static condition during exposure. In the case of a race horse, this presents two dangers: (1) that the assistant will be subject to being kicked or trampled on by the race horse, and (2) subject the technician to unnecessary exposure to X radiation.